/* -------------------------------------------------------------------------
 *
 * mingwcompat.c
 *	  MinGW compatibility functions
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *	  src/backend/port/win32/mingwcompat.c
 *
 * -------------------------------------------------------------------------
 */

#include "postgres.h"
#include "knl/knl_variable.h"

#ifndef WIN32_ONLY_COMPILER
/*
 * MingW defines an extern to this struct, but the actual struct isn't present
 * in any library. It's trivial enough that we can safely define it
 * ourselves.
 */
const struct in6_addr in6addr_any = {{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}};

/*
 * This file contains loaders for functions that are missing in the MinGW
 * import libraries. It's only for actual Win32 API functions, so they are
 * all present in proper Win32 compilers.
 */
static HMODULE kernel32 = NULL;

/*
 * Load DLL file just once regardless of how many functions
 * we load/call in it.
 */
static void LoadKernel32()
{
    if (kernel32 != NULL)
        return;

    kernel32 = LoadLibraryEx("kernel32.dll", NULL, 0);
    if (kernel32 == NULL)
        ereport(FATAL, (errmsg_internal("could not load kernel32.dll: error code %lu", GetLastError())));
}

/*
 * Replacement for RegisterWaitForSingleObject(), which lives in
 * kernel32.dll
 */
typedef BOOL(WINAPI* __RegisterWaitForSingleObject)(PHANDLE, HANDLE, WAITORTIMERCALLBACK, PVOID, ULONG, ULONG);
static __RegisterWaitForSingleObject _RegisterWaitForSingleObject = NULL;

BOOL WINAPI RegisterWaitForSingleObject(PHANDLE phNewWaitObject, HANDLE hObject, WAITORTIMERCALLBACK Callback,
    PVOID Context, ULONG dwMilliseconds, ULONG dwFlags)
{
    if (_RegisterWaitForSingleObject == NULL) {
        LoadKernel32();

        _RegisterWaitForSingleObject =
            (__RegisterWaitForSingleObject)GetProcAddress(kernel32, "RegisterWaitForSingleObject");

        if (_RegisterWaitForSingleObject == NULL)
            ereport(FATAL,
                (errmsg_internal(
                    "could not locate RegisterWaitForSingleObject in kernel32.dll: error code %lu", GetLastError())));
    }

    return (_RegisterWaitForSingleObject)(phNewWaitObject, hObject, Callback, Context, dwMilliseconds, dwFlags);
}

#endif
